Vibronic measuring devices for determining fill level, density, and/or viscosity of a medium are known in the form of oscillatory forks, membrane oscillators and single rods. Common to these vibronic measuring devices is that they possess an oscillatable unit, which is excited to execute resonant oscillations. The excitation occurs, most often, via piezoelectric elements. Drive elements and the oscillatable unit together form the sensor unit. The mechanical oscillations are converted into electrical, received signals and their frequency, amplitude, and/or phase shift evaluated relative to the excitation signal. This is done advantageously digitally in a microcontroller, which is fed the received signal via an analog-digital converter. The excitation signal can be produced likewise in the microcontroller with a predetermined phase shift relative to the received signal and, for example, fed via a digital-analog converter to the drive elements of the oscillatable unit. The amplitude of the received signal varies as a function of the damping of the oscillations of the oscillatable unit. The sensor unit of vibronic measuring devices possesses, consequently, as a rule, a very high dynamic range. The analog-digital converter must possess a correspondingly high resolution, in order to be able to digitize all signals. The resolution of analog-digital converters integrated into microcontrollers is, however, limited and insufficient for such a high dynamic range, so that the range, in which the measuring device can determine the process variable reliably, is limited.